Empty Display Control Readings

# Improve screen reader announcements

## sap.m.Text empty indicator

sap.m.Text allows developers to show to users when text is empty with a “–” character. Depending on the language the symbol (“–”) may change.

    new sap.m.Text({
    	text: "",
    	emptyIndicatorMode: sap.m.EmptyIndicatorMode.On
    })

## sap.m.Table cell with empty indicator display

You have to set `visible` property to `false` for all `sap.m.Link` and `sap.m.Text` control’s instances that are used inside a `sap.m.Table` cell and have empty `text` property. Same should be done for `sap.m.ObjectIdentifier`’s instances that have empty `title` property. This will improve the screen reader announcements of `sap.m.Table` rows or `sap.m.List` items as all visually empty cells or items will be announced as "empty".

    new sap.m.Table({
    	headerToolbar: new sap.m.OverflowToolbar({
    		content: [
    			new sap.m.Title({
    				text: "Products",
    				level: "H2"
    			})
    		]
    	}),
    	columns: [
    		new sap.m.Column({
    			header: new sap.m.Text({
    				text: "Product Name"
    			})
    		}),
    		new sap.m.Column({
    			header: new sap.m.Text({
    				text: "Supplier Name"
    			})
    		}),
    		new sap.m.Column({
    			header: new sap.m.Text({
    				text: "Description"
    			})
    		})
    	],
    	items: [
    		new sap.m.ColumnListItem({
    			cells: [
    				new sap.m.Link({
    					text: "",
    					href: "",
    					visible: false,
    					tooltip: "Audio/Video Cable Kit - 4m"
    				}),
    				new sap.m.ObjectIdentifier({
    					title: "Titanium",
    					titleActive: true
    				}),
    				new sap.m.Text({
    					text: "Quality cables for notebooks and projectors"
    				})
    			]
    		}),
    		new sap.m.ColumnListItem({
    			cells: [
    				new sap.m.Link({
    					text: "Blaster Extreme",
    					href: ""
    				}),
    				new sap.m.ObjectIdentifier({
    					title: "",
    					titleActive: true,
    					visible: false,
    					tooltip: "Speaker Experts"
    				}),
    				new sap.m.Text({
    					text: "PC multimedia speakers - 10 Watt (Total) - 2-way"
    				})
    			]
    		}),
    		new sap.m.ColumnListItem({
    			cells: [
    				new sap.m.Link({
    					text: "Copymaster",
    					href: ""
    				}),
    				new sap.m.ObjectIdentifier({
    					title: "Alpha Printers",
    					titleActive: true
    				}),
    				new sap.m.Text({
    					text: "",
    					visible: false,
    					tooltip: "Copymaster"
    				})
    			]
    		})
    	]
    })